Glass insulator assembly units



Jan. 20, 1959 P. E. JELLYMAN ETAL 2,870,244

GLASS INSULATOR ASSEMBLY UNITS Filed June 21, 1955 vPhilip E. Jellyman,Eccleston, St. Helens,

GLASS INSULATOR ASSEMBLY UNITS England,

Hamish Fraser Macintosh, Brora, Sutherland, Scotland, and John E.Wilcock, St. Helens, England, assignors y to Pilkington BrothersLimited, Liverpool, England, a l company of Great Britain ApplicationJune 21, 1955, Serial No. 516,948

6 Claims. (Cl. 174-165) in similar manner a mounting pin for theassembly, which pin is shrouded by an externally threaded copperferrule.

Such an assembly is employed for carrying an electrical power cable,which latter is rested in a recess at the top of the head of the uppershed and is held in situ by a binding wire coiled about the head andabout each part of the cable-,adjacent to the head.

The glass sheds are produced by a pressing operation effected in a mouldon a charge of molten glass.

The head of the outer shed is usually shrouded by a suitable metal capto hold it together if it should be fractured. p Y

In :3o-pending application No. 486,962 is described an alternativemethod of effecting the restricted extraction of heat from the zoneprior to chilling the glass to produce a toughened glass shed, thisalternative method involving the appliaction of a stream of air to thatarea in the skirt and near the head intended to form the zone which actsas the barrier in the manner already described.

In the process described in the said co-pending application there is apartial extraction of heat, effected as quickly as possible, from theannular body of glass in the skirt and near the head intended to formthe zone, this extraction being effected immediately after the insulatorhas -been withdrawn from-the temperature equalising furnace by heatexchange with air directed on to the annular body of glass, so that thedesired temperature difference between the lglass in the annulus and theambient glass in" the insulator is obtained, `and immediately a rapidchilling of the outer and inner surfaces of the insulator to toughen theinsulator is effected.

In a second co-pending patent application No. 516,992 a further methodof protecting the head of an upper shed is described in which the skirtis formed during the pressing operation with a delineated zone which isof somewhat less thickness than the ambient glass, as already described,and then the whole insulator is cooled by simultaneously andsymmetrically directing gentle streams of cooling gas, for example airor steam, on to the whole external and internal surface of the insulatorafter it has left the temperature equalising furnace, so that a slightlytoughened product results, that is to say, the degree of tougheningobtained'is not such as to produce dicing on a fracture occurring in theglass; but experiments have shown that an insulator thus obtained isapproxi- United States Patent O mately three times as strong as aninsulator which is completely annealed in the well known manner.

The main object of the present invention is to devise a form of lowershed for insulator assemblies of the kind described which will assist inprotecting the head of the upper shed against the effect of the impactof missiles projected from the ground, for example by catapulta againstthe head when incorporated in a unit assembly.

In accordance with the present invention an insulator assembly unitincluding a glass insulator (upper shed), a lower shed and a mountingpin is characterised in that the glass insulator comprises a hollowhead, a skirt having a radial portion emanating from the base of thehead, an annular zone in the radial portion of the skirt, which zone hasbeen thermally treated to prevent the propagation of a fractureinitiated in the part of the skirt below the zone, through the zoneupwards to the head, and the lower shed comprises a hollow head locatedwithin the head of the upper shed and a skirt emanating from the head ofthe lower shed in downward land outward direction to form an annularledge below the said annular zone just below the level of the bottomedge of the insulator skirt, and an external annular cavity formed underthe said ledge adapted to outwardly deflect missiles projected at thehead of the insulator from ground level when the assembly is fixed inoperative position.

The part of the skirt of the lower shed forming the wall of the annularcavity may be thermally treated to produce in the wall an annular zoneadapted on toughening the insulator to prevent the ,propagation of afracture in the lower part of the lower shed to the upper part thereof.

The zone in the lower shed may be delineated during the pressingoperation, and to this end the wall of the cavity may be formed with anannular zone which is of somewhat less thickness than that of theambient glass, the upper and under surfaces of the zone being continentwith the surfaces of the ambient glass, the zone thus formed beingthermally treated as a precedent to toughening the insulator to form thezone into a barrier against the propagation of a fracture in the lowerpart of the lower shed to the upper part thereof.

ln order that the present invention may be more clearly understood, apreferred embodiment thereof in an assembly unit including an insulatoras an upper shed partially toughened as described in the said secondcopending patent application No. 516,992 will now be described by way ofexample, with reference to the accompanying diagrammatic drawing whichis a central vertical section of the unit.

The glass insulator (upper shed) which is intended to be used forsupporting power lines is a pressing'whch comprises a hollow head 1including a recess 2, for a power line, at the top of the vertical axis3 3, and an annular shoulder 4 below which is an annular recess 5adapted to receive the usual binding wire for the line, the pressingalso including radially outward (i. e. at right angles from the axis 33) from the bottom of the recess 5 a skirt 6, the bead being extendedbelow the top of the skirt to produce the base 7 of the head.

Generally speaking, therefore, the hollow head is of cylindrical formwith a recess top and sides, firmly set within the upper part of theskirt, which latter is thickest at the bottom and progressivelydecreases in thickness towards a zone in the upper part of the skirt asnow to be described.

ln the radial portion of the skirt 6 and near to the head 1 an annularzone 8 having a mean width of about half an inch is formed during thepressing operation, which zone is of minimum thickness in the middle,and symmetrically increases in thickness from the middle of the zone,which latter is de'ned by the chain lines 9 9, the upper and undersurfaces of the zone being confluent with the surfaces of the ambientglass. The skirt 6 progressively increases in thickness on the outsideof the zone towards the rim 1.0 ofthe skirt, and on the inner sidetowards the base 7 of the heath, the zone 8 having a convex face l1 onthe outside and a concave face 12 on the inside.

The interior of the head i in known manner provides a socket 13 with twopockets 14, each extending substantially halfway around. the interior ofthe head, said socket receiving the hollow head 15 of a glass lower shedcomprising a skirt 16. A cementitious lining 17 to the head l. lls thespace between the heads l and l5 including the pockets 14 and makes aninterlocking joint therebetween. The interior of the head 15 likewiseforms a socket for the top of the usual mounting pin llti which isshrouded by an externally threaded copper errule 19, the latter beinginterlocked with the head 15 by a cementitious lining 2% therein. Thusthe pin 18, the lower glass shed Iii-"i6 and the insulator i-G form anintegral whole which carries a line indicated at 21 held to the unitassembly by a binding wire 22.

As clearly shown in the drawing, the skirt 16 of the lower shed isflared outwardly immediately from the base of the head J5 and extendsoutwards practically as far the zone i in the upper shed (as viewed inplan) and forms an annular ledge 23 below the zone and in a plane justbelow thc level of the bottom edge ot the skirt 6 ot the upper shed.

immediately below the ledge 23 the skirt 16 is formed to define externalannular cavity 24 so devised that it hit by a stone, for examplecatapulted from the ground, the wall of the cavity will deflect thestone from its path of projection outwardly from the assembly or atleast so that, if it hits the rim of the skirt 6 below the zone 8 anydamage is very much restricted.

The cavity Wall may be thermally treated to produce a zone 25 which thenacts as a barrier if the lower shed is fully toughened as fullydescribed in the aforesaid co-pending application 486,962 but the zonemay be delineated in the same manner as zone S in the pressing operationby which the lower shed is produced, so that as a result of partiallytoughening the lower shed in the same manner as the' upper shed, anelective barrier is constivtuted by the zone 2S to the propagation of afracture through the zone.

ln such arrangement the annular zone 25 is of somewhat less thicknessthan that of the ambient glass in the insulator.

By the present invention very effective protection is given to the uppershed of the unit assembly against iracture by missiles directed againstit from ground level.

By utilizing the constructural forms of insulator sheds irereinbeforedescribed a mechanically sound insulator structure is devised, after thepressed article has been subjected to the usual temperature equalisingtreatment and then cooled in the manner described, and an insulator ofsufficient strength is produced to carry not only the normal load otlthe line', but also the seasonal extra loads such as are produced bysnow and other condi tions derived from low temperatures.

We claim:

l. An insulator assembly unit comprising a glass insulator', a lowershed and a mounting pin characterised in that the glass insulatorcomprises a hollow head, a skirt having a radial portion emanating fromthe base of the bead, an annular zone in the radial portion of the shirtadapted to prevent the propagation of a fracture initiated in the partof the skirt below the zone, through the zone upwards to the head, andthe lower shed com pries a hollow head located within the head of theinsulator and a skirt emanating radially from the head of ti; lowershed, the upper surface of the skirt emanating in an outward and thendownward direction to form firstly an annular ledge positioned beneaththe said annular zone at a level just below the level of the bottom edgeot the insulator skirt, and then an external arcuate an nular cavityopening under the said ledge adapted to deiiect outwardly missiles shotat the head of the insulator when the assembly is fixed in position fromground level.

2. An insulator assembly unit according to claim l, wherein the annularzone in the skirt of the glass insulator comprises glass toughencd to alesser degree than the ambient glass.

3. An insulator assembly unit according to claim l', wherein the annularzone in thc skirt of the glass insulator is of somewhat less thicknessthan that of the ambient glass, the upper and under surfacesl of thezone being continent with the surfaces of the ambient glass and thewhole of the glass insulator being slightly toughened.

4. An insulator assembly unit according to claim l, wherein the wall ofthe cavity is formed with an annular zone which comprises glasstoughened to a lesser degree than the ambient glass.

5. An insulator assembly according to claim l wherein the part of theskirt of the lower shed forming the wall of the annular cavity comprisesan annular zone adapted to prevent the propagation of a fracture in thelower part of the lower shed to the upper part thereof.

6. An insulator assembly according to claim l wherein the wall of thecavity is formed with an annular zone which is of somewhat lessthickness than that of the ambient glass, the upper and under surfacesof the zone being continent with the surfaces of the ambient glass, andthe whole of the lower shed being slightly toughened.

References Cited in the file of this patent UNITED STATES PATENTS1,192,690 Scbaakc l'uly 25, 1916 .2,162,288 Taylor June 13, 19392,418,713 Holmes et al. Apr. 8, 1947 FOREIGN PATENTS 524,663 GreatBritain Aug. l2, 1940 UNITED STATES PATENT oEFIcE CERTIFICATE OFCORRECTION Patent No. V2,8"7C5244 January 20, 1959 Philipv ET,Jellymanet al.,

It is hereby certified that error appears inl the above numbered patentrequiring correction and that the said vLetters Patent should read ascorrected below.

n, between lines 8 and 9 In the heading of the printed specificati@Great Britain July 26, M954 o thereof, insert Claims priority,application Signed and sealed this 30th day of June 1959.

C .(sE-AL) Attest: i

KARLH- AXLIN ROBERT c. wATsoN Attesbng'lofflcer Commissioner of PatentsUNITED STATES PATENT oEFIcE CERTIFICATE OF CORRECTION Patent No.V2,8"7C5244 January 20, 1959 Philipv ET, Jellymanet al.,

It is hereby certified that error appears inl the above numbered patentrequiring correction and that the said vLetters Patent should read ascorrected below.

n, between lines 8 and 9 In the heading of the printed specificati@Great Britain July 26, M954 o thereof, insert Claims priority,application Signed and sealed this 30th day of June 1959.

C .(sE-AL) Attest: i

KARLH- AXLIN ROBERT c. wATsoN Attesbng'lofflcer Commissioner of PatentsUNITED STATES PATENT OFFICE -1- CERTTFICATE 0F CORRECTION January 20,1959 Patent No. 2,870,244

Philip'Ea Jellyman et al It is hereby certified that error appears inthe above numbered patent requiring correction and that the said LettersPatent should read as corrected below.

In the heading of the printed specification, between lines 8 and 9thereof, insert Claims priority, application Great Britain July 26, 1954w Signed-and sealed this 30th day of June i959n .(SEAL) Attest: i

KARLH- AXLINE l p ROBERT c. wATsoVN, l Conmissoner of Patentsttesting-Oificer

